Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from queue import Queue
h,w = map(int, input().split(' '))
s = [list(input()) for _ in range(h)]
num_w = 0
for i in range(h):
    num_w += s[i].count("#")
for i in range(h):
    s[i] = ["#"]+s[i]+["#"]
s.insert(0,["#" for i in range(w+2)])
s.append(["#" for i in range(w+2)])
q = Queue()
cnt = 0
q.put([1,1,0])
s[1][1]="#"
Z = -1
while (not q.empty()):
    x,y,cnt = q.get()
    if (x,y) == (h,w):
        Z = cnt
        break
    for (i,j) in [(x+1,y),(x-1,y),(x,y+1),(x,y-1)]:
        if s[i][j] != "#":
            s[i][j] = "#"
            q.put([i,j,cnt+1])
if Z == -1:
    print(-1)
else:
    print(h*w-Z-1-num_w)